It is proposed to study the role of cellular membranes in the cytotoxicity of the antineoplastic agent adriamycin. Although the paradigm for the mechanism of action of this drug has been interference with DNA fuunction, a variety of experiments suggest that membrane actions may be equally or more important. To further explore this idea we have covalently linked adriamycin to agarose beads. This immobilized adriamycin will be used to study the interaction of the drug with the plasma membrane of cultured tumor cells without permitting the drug to penetrate the cell interior. In order to clarify the molecular mechanisms of drug-membrane interaction, it is also proposed to carry out some physiochemical studies of the interaction of adriamycin with liposomes. These experiments are designed to answer such basic questions as how does adriamycin alter membrane fluidity, where in the bilayer does the bound drug reside, what is the kinetic mechanism of interaction, what intermediates are formed and what are their lifetimes, and what is the time scale of adriamycin binding to phospholipid bilayers? Moreover, evidence for a role of the phospholipid cardiolipin in drug specificity is presented and experiments aimed at exploring the phenomenon are described.